Formed front header for a dock leveler

ABSTRACT

A dock leveler includes a pivotally extendable lip coupled to a pivotal deck by way of a front hinge, wherein the structure in the area of the front hinge optimizes the torsional flexibility of the deck; provides a well supported, durable crown (apex angle between an extended lip and the deck); and reduces the part count of the dock leveler. The front hinge includes a deck-hinge member that extends approximately the full width of the deck and is preferably formed from a single sheet of material. A particularly narrow front header or flange disposed along the front edge of the deck reinforces the relatively thin deck plate so that the plate&#39;s rigidity more closely matches that of the thicker lip, yet the flange is sufficiently small to allow the deck to twist so that the deck can place the tip of the lip squarely upon a sideways inclined truck bed.

This Application is a Divisional of U.S. patent application Ser. No.10/902,458, filed on Jul. 29, 2004, which is incorporated herein byreference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The subject invention generally pertains to dock levelers and morespecifically to the structure around a hinge that pivotally connects alip extension plate to the deck of a dock leveler.

2. Description of Related Art

A typical truck loading dock of a building includes an exterior doorwaywith an elevated platform for loading and unloading vehicles such astrucks and trailers. Many loading docks have a dock leveler tocompensate for a height difference that may exist between the loadingdock platform and an adjacent bed of a truck or trailer. A typical dockleveler includes a deck that is hinged along its back edge so that thedeck can pivotally adjust the height of its front edge to an elevationthat generally matches the height of the rear edge of the truck bed.

In addition, usually a front hinge pivotally connects an extension plateor lip to the front edge of the deck. The front hinge allows the lip topivot between a stored, pendant position and an extended, operativeposition. In the extended position, the lip can rest upon the truck bedto form a bridge between the deck and the bed. This allows personnel andmaterial handling equipment, such as a forklift truck, to readily moveon and off the vehicle during loading and unloading operations.

The design of the front hinge and the adjoining structure determinessome key features of the dock leveler. These features include the crown,openness of the front hinge, flexibility of the deck, and part count.

First, the crown is the angle or apex created between the upper surfacesof the deck and an extended lip. The crown angle is usually about two orthree degrees less than 180 degrees, and it becomes an important featurewhen the truck bed is higher than the platform from which the deckextends. When the truck bed is higher than the platform, the deck mustlie at an incline to elevate the deck's front edge. If the lip werecoplanar with the deck, whereby no crown existed, the lip would projectits distal edge (tip of the lip) a little above the truck bed. Thiswould create a detrimental step between the tip of the lip and the truckbed, wherein the step might trip dockworkers or jar forklifts. A crowneliminates this step by pointing the tip of the lip back down againstthe truck bed.

It can be difficult, however, to maintain a desired crown as the weightof a forklift repeatedly carrying loads over the front hinge area of thedock leveler generates tremendous forces that tend to flatten the crownover time. Numerous hinge and lip structures have been devised tocounter such forces; however, many of them rely on a single abutmentsubjected to high stress concentrations. A common example of such anabutment would be the back edge of the lip abutting the front edge ofthe upper deck plate. With such a design, high stress concentrations caneventually wear down the abutment to diminish or eliminate the crown.Other dock levelers, such as disclosed in U.S. Pat. No. 5,815,871,involve assemblies having intricate cross-sectional shapes that can beexpensive to produce.

The second mentioned feature of the dock leveler pertains to theopenness of the front hinge, which connects the lip to the deck. Theopenness refers to any gaps that may exist at the hinge when the lip isat its pendant position. U.S. Pat. No. 3,587,126 provides an example ofa dock leveler whose front hinge is of an open design, while U.S. Pat.No. 6,370,719 shows a hinge of a more closed design. Although eitherstyle may function well, some believe that a closed-style hinge lookscleaner, provides less of a pinching hazard, and prevents items fromaccidentally falling between the pendant lip and the deck.

Third, torsional flexibility of the deck or the ability of the topsurface of the deck to twist out of its normal plane of flatness isanother important feature of a dock leveler. Such flexibility allows thedeck to twist so that the front edge of the deck and the lip extendingfrom it can align themselves to the plane of the truck bed. Forinstance, if the dock platform is level but the truck bed lies at anangle from the right to left side of the truck, the deck can twistaccordingly.

The deck's torsional flexibility is partially determined by theexistence or absence of a front header. When present, the front headerusually lies just behind the front hinge and extends generallyperpendicular to a series of beams that support the upper plate of thedeck. These beams are typically welded or other wise affixed to theheader—which thus serves to structurally tie the beams together. Often,the front hinge is mounted directly to the front header. U.S. Pat. No.6,370,719 shows an example of a dock leveler with a front header, andU.S. Pat. No. 3,587,126 shows one without a header. Some decks withheaders are torsionally too stiff, while other decks without headers canbe too flexible. Without a header, the top plate of the deck may be soflexible and unsupported that the weight of forklifts may deform theplate in the areas between its supporting beams, whereby the platebecomes permanently dished down in those areas.

Fourthly, the part count of a front hinge assembly can have a directaffect on the cost of a dock leveler. Generally, the number of parts ispreferably kept to a minimum, which can be difficult to do when thehinge assembly comprises a series of spaced-apart hinge segments thatare pivotally connected by a hinge pin.

Consequently, a need exists for a front header and hinge assembly thatprovides a dock leveler with a minimal number of parts, a long lastingcrown, a generally closed hinge, and a deck with appropriateflexibility.

SUMMARY OF THE INVENTION

In some embodiments, a dock leveler includes a front hinge thatpivotally connects a lip to a deck of the leveler, wherein the fronthinge includes a formed deck-hinge member that extends between at leasttwo of the deck's support members.

In some embodiments the formed deck-hinge member extends along most ofthe deck's width.

In some embodiments, the front hinge of the dock leveler closes most ofthe gap between the lip and the deck when the lip is at the pendantposition.

In some embodiments, the front hinge comprises a deck-hinge memberpinned to a plurality of lip-hinge members, wherein the plurality oflip-hinge members extend into a corresponding plurality of apertures inthe deck-hinge member.

In some embodiments, the deck-hinge member has a plurality of slits forengaging a plurality of support beams underneath the top plate of thedeck.

In some embodiments, the lip in an extended position engages a frontedge of the deck and an upper surface of the deck-hinge member to ensurethat a crown or apex exists where the lip and deck meet.

In some embodiments, the deck includes a narrow front header or flangethat provides the deck with a desired amount of torsional flexibilitywhile supporting the deck plate at it's free edge to help preventdeformation in the areas between the deck's support beams.

In some embodiments, the front header provides the front edge of thedeck's top plate with a level of flexibility that is comparable to thatof the lip even though the average material thickness of the lip isgreater than that of the top plate.

In some embodiments, the bottom edge of the front header is above thelongitudinal centerline of the front hinge pin.

In some embodiments, the bottom edge of the front header is above thefront hinge pin.

In some embodiments, the bottom edge of the front header is above thedeck-hinge member.

In some embodiments, the deck-hinge member engages the hinge pin along acurved surface that extends less than 360-degrees around the hinge pin.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a truck at a loading dock, wherein the dockincludes a dock leveler whose deck and lip are at their storedpositions.

FIG. 2 is side view similar to FIG. 1 but showing the deck rising andthe lip extending.

FIG. 3 is a side view similar to FIGS. 1 and 2 but showing the deckhaving lowered the lip upon the bed of the truck.

FIG. 4 is a perspective view of the dock leveler of FIG. 3.

FIG. 5 is a perspective view of a deck-hinge member used in the dockleveler of FIG. 1.

FIG. 6 is a close-up side view of the dock leveler of FIG. 3 but with aside plate of the deck removed to show details of the front hinge.

FIG. 7 is similar to FIG. 6 but showing the lip in a pendant position asalso shown in FIG. 1.

FIG. 8 is a perspective view of another embodiment of a dock leveler.

FIG. 9 is close-up side view similar to FIG. 6 but for the dock levelerof FIG. 8.

FIG. 10 is close-up side view similar to FIG. 7 but for the dock levelerof FIG. 8.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIGS. 1-3, in order to compensate for a height differentialthat may exist between a loading dock platform 10 and the bed of a truck12, a dock leveler 14 includes a ramp or deck 16 that can pivot aboutits back edge 18 to adjust the height of its front edge 20. To bridgethe gap between the deck's front edge 20 and the rear edge of truck 12,a front hinge 22 pivotally connects a lip 24 to the deck's front edge20. Deck 16 is movable between a raised position (FIG. 2) and a loweredposition (FIG. 1), and lip 24 can pivot between an extended position(FIG. 3) and a pendant position (FIG. 1).

In operation, truck 12 backs into the loading dock, adjacent to platform10, as shown in FIG. 1. At this point, deck 16 is at its stored,cross-traffic position where a driveway surface 26 of deck 16 isgenerally flush with platform 10. Also, lip 24 is shown at its pendantposition where, in some embodiments, a tip 28 of lip 24 rests upon a setof lip keepers 30.

Next, referring to FIG. 2, deck 16 rises and lip 24 swings out to extendthe tip 28 of lip 24 out over the top of the truck bed.

Then, in FIG. 3, deck 16 descends to place the extended lip 24 upon thebed of truck 12. The movement of lip 24 and deck 16 can be carried outin any of a wide variety of ways that are well known to those ofordinary skill in the art. The movement, for example, can be powered,manually driven, or a combination of the two. Mechanisms for moving deck16 or lip 24 include, but are not limited to, hydraulic cylinder orbladder, pneumatic cylinder or bladder, mechanical linkage, drive screw,rack and pinion, winch, mechanical spring, gas spring, and variouscombinations thereof.

Regardless of how deck 16 and lip 24 are moved, an important aspect ofthe invention pertains to front hinge 22 and its surrounding structure.It is this part of dock leveler 14 that helps determine the crown (anglebetween deck surface 26 and extended lip 24), openness of hinge 22, andthe torsional flexibility of deck 16. In this first embodiment, hinge 22is of a closed design and is mounted adjacent to a narrow front headeror flange 32 (FIGS. 6 & 7). Hinge 22 and flange 32 are purposefullydesigned to increase the strength of the crown, optimize the torsionalflexibility of the deck, and minimize total part count of the dockleveler.

Hinge 22, for instance, includes a deck-hinge member 34 cut and formedfrom a single sheet of material (see FIG. 5) and welded or otherwiseattached to deck 16. Preferably, that attachment to deck 16 isaccomplished by deck-hinge member 34 having several slits 36 forengaging a series of central support members or beams 38 to which deckhinge member 34 is welded and that support a deck plate 40 of deck 16.Deck-hinge member 34 may also be welded or otherwise attached to sidesupport members 39. Accordingly, deck-hinge member 34 serves tostructurally tie together the support members (both central and side) ina similar manner to a conventional front header—while also serving thefunction of creating the deck portion of the hinge structure. In theembodiment shown FIGS. 4-7, the deck-hinge member is a unitary piececonnecting all of the deck support members and thus extending along mostof the width of the deck 16. Alternatively, individual deck-hingemembers could extend between and structurally tie together less that allof the deck support members—such as a pair of deck support members.Either form of deck-hinge members would perform both their hingefunction as well as the function of extending between and thusstructurally tying together two or more deck support members. Deck-hingemember 34 may be provided with pin-retaining bars 41 that help maintainthe radial position of hinge pin 50 relative to deck-hinge member 34. Ifneeded, one or more sections 42 of deck-hinge member 34 can be notchedout to provide operating clearance for a lip actuator. Deck-hinge member34 defines a plurality of apertures 44 for receiving an equal pluralityof lip-hinge members 46.

Referring to FIGS. 6 and 7, lip-hinge members 46 according to thisillustrative embodiment are U-shaped pieces that are welded or otherwiseattached to a lower surface 48 of lip 24. With lip-hinge members 46extending into apertures 44 of deck-hinge member 34, a hinge pin 50 canbe inserted between members 34 and 46 to pivotally couple lip 24 to deck16, whereby lip 24 can pivot about a longitudinal centerline 52 of pin50.

For simplicity, less frictional contact area, and ease of manufacturing,deck-hinge member 34 has a curved pin-engaging surface 54 that contactspin 50 over an area of less than 360 degrees, as indicated by arc 56 ofFIG. 6. Likewise, lip-hinge member 46 also has a curved pin-engagingsurface 58 that contacts pin 50 over an area of less than 360 degrees,as indicated by arc 60 of FIG. 7.

To maximize the strength and minimize the part count of the front hingeassembly, deck-hinge member 34 preferably extends seamlessly along mostif not all of its length, or the width of deck 16, or the length of pin50. The term “seamlessly” refers to a part made from one continuouspiece and/or along which a straight or winding path can be tracedgenerally lengthwise without encountering a seam or joint.

To establish a crown 62 (FIGS. 3 and 6) that can withstand heavy,repeated loading, the upward movement of lip 24 is limited by a backedge 64 of lip 24 abutting front edge 20 and/or lower surface 48 of lip24 engaging an upper surface 66 of deck-hinge member 34. The crown angle68 or apex between an upper lip surface 70 of lip 24 and the drivewaysurface 26 of deck 16 is typically about 5-degrees (angle 72) less than180-degrees. Ideally, lip 24 abuts front edge 20 and upper surface 66simultaneously to form crown angle 68, thereby creating a two-pointcrown control which aides in the longevity of maintaining a desired lipcrown by distributing the repeated load of a traversing fork truck.

To provide deck 16 with an appropriate amount of torsional flexibility,flange 32 (FIGS. 6 & 7) is made particularly narrow. The deck-hingemember 34 performs some of the function of a conventional header bystructurally tying two or more deck support members together, such thatthe addition of flange 32 provides the appropriate amount of torsionalrigidity allowing deck 16 to twist so that the tip 28 of lip 24 can liesquarely atop the bed of truck 12 even when the truck bed and platform10 are at an angle to each other (as measured from the left to rightside of the truck).

Since deck plate 40 is supported by beams 38 and side supports 39, plate40 may be thinner than lip 24. So, to prevent plate 40 from permanentlydeflecting or bowing downward in the areas between beams 38 and betweenbeams 38 and side supports 39, or at least to prevent front edge 20 fromdeflecting much more than lip 24, flange 32 preferably provides frontedge 20 of deck 16 with a level of rigidity that is comparable to thatof lip 24. Because deck-hinge member 34 performs some of this functionitself, flange 32 can be smaller than a conventional header, such asbeing of a height that places a lower edge 74 of flange 32 at anelevation that is above the lower extremity 51 of the hinge pin 50. Asshown here, the lower edge 74 is above the hinge pin's centerline 52 andpreferably higher than pin 50 itself. Although flange 32 is shown as aseparate piece that is welded or otherwise attached to deck plate 40,alternatively, the front edge of plate 40 could be formed or bentdownward to create a flange that extends integrally from plate 40,whereby deck plate 40 and flange 32 would be a unitary piece. It shouldbe noted that flange 32 is disposed vertically between the bottom offront edge 20 and the upper surface 66 of the deck-hinge member 34. Thisposition of flange 32 allows it to transfer loads applied to the freefront edge 20 (particularly the length thereof between the supportmembers or beams) into the deck-hinge member 34 and thus to the supportmembers or beams to which member 34 is attached.

The relatively narrow flange 32 can also be used on a dock leveler 76that has a front hinge 78 of a more open design, as shown in FIGS. 8-10.In this case, hinge 78 comprises a series of lip-hinge members 80connected to a lip 82 and a series of deck-hinge members 84 attached toa deck 16′. Hinge pin 50 joins members 80 and 84 to render lip 82pivotal relative to deck 16′.

To establish a crown 86 (similar to previously mentioned crown 62) thatcan withstand heavy, repeated loading, the upward movement of lip 82 islimited by a back edge 88 of lip 82 abutting a front edge 90 of deck 16′and/or a lower surface 92 of lip 82 engaging an upper surface 94 ofdeck-hinge member 84. Ideally, lip 82 abuts front edge 90 and uppersurface 94 simultaneously to form crown 86, thereby creating a two-pointcrown control which aides in the longevity of maintaining a desired lipcrown. Again, flange 32 is compressed between the free front edge of thedeck and the deck hinge members 84 for applied loads. This facilitatesthe transfer of those loads to the support members or beams to whichdeck-hinge members 84 are attached thereby reinforcing the free frontedge of the deck.

Although the invention is described with reference to a preferredembodiment, it should be appreciated by those of ordinary skill in theart that various modifications are well within the scope of theinvention. Therefore, the scope of the invention is to be determined byreference to the following claims:

1. A dock leveler, comprising: a deck that includes a driveway surfaceand a front edge, wherein the deck is movable between a raised positionand a cross-traffic position; a lip with an upper and lower surface anda back edge, and that is pivotally coupled to the deck such that the lipis pivotal between an extended position and a pendant position; adeck-hinge member that includes an upper hinge surface, wherein thedeck-hinge member extends from the deck; a lip-hinge member extendingfrom the lip; and a hinge pin coupling the lip-hinge member to thedeck-hinge member, thereby pivotally coupling the lip to the deck suchthat the lip is movable relative to the deck-hinge member and when thelip is in the extended position, the upper lip surface and drivewaysurface create an apex when the back edge of the lip engages the frontedge of the deck and the lower lip surface engages the upper hingesurface.
 2. The dock leveler of claim 1, wherein contact between theback edge of the lip and the front edge of the deck and the lower lipsurface and the upper hinge surface maintains the apex for appliedloads.
 3. The dock leveler of claim 1, wherein the deck-hinge memberextends along most of the width of the deck.
 4. The dock leveler ofclaim 3, wherein the deck-hinge member and the lip-hinge members close amajority of a gap that exists between the lip and the deck when the lipis at the pendant position.
 5. The dock leveler of claim 1, wherein theupper hinge surface is substantially flat and lies at a non-zero angleto the driveway surface of the deck, so that the upper hinge surface andthe driveway surface are not parallel.
 6. The dock leveler of claim 1,wherein the deck plate has a deck width, and a front edge, andcomprising a lip-hinge member attached to the lip to pivotally couplethe lip and deck with a hinge pin, and further comprising a flange lyingadjacent to the front edge, running along most of the deck width, andextending downward from the deck plate to a lower edge of the flange,wherein the lower edge of the flange is higher than a lower extremity ofthe hinge pin when the deck is at the cross-traffic position.
 7. Thedock leveler of claim 1, comprising a plurality of deck-hinge membersand a plurality of lip hinge members, wherein each of the plurality ofdeck-hinge members is attached to a support member and each has an upperhinge surface.
 8. A dock leveler, comprising: a deck that includes adeck plate supported by a plurality of support members the deck platehas a deck width, a front edge, and a plate material thickness, and thedeck is movable between a raised position and a cross-traffic position;a lip being pivotally coupled to the deck adjacent to the front edgesuch that the lip is pivotal between an extended position and a pendantposition; a hinge pin that pivotally couples the lip to the deck suchthat the lip can pivot relative to the deck about a longitudinalcenterline of the hinge pin; and a flange lying adjacent to the frontedge, running along most of the deck width, and extending downward froman undersurface of the deck plate to a lower edge of the flange, whereinthe lower edge of the flange is higher than a lower extremity of thehinge pin when the deck is at the cross-traffic position.
 9. The dockleveler of claim 8, and further comprising a deck-hinge member attachedto at least one of the plurality of support members, the flange beingdisposed between deck front edge and an upper surface of the deck-hingemember to transfer a load applied to the front edge to the supportmember.
 10. The dock leveler of claim 9, wherein the deck-hinge memberand the flange extend along most of the width of the deck.
 11. The dockleveler of claim 8, further comprising a deck-hinge member attached tothe deck and a lip-hinge member attached to the lip, wherein the hingepin pivotally couples the lip-hinge member to the deck-hinge member topivotally couple the lip to the deck, wherein the deck-hinge memberincludes an upper surface that is substantially flat and lies at anon-zero angle to the deck plate, so that the upper surface of thedeck-hinge member and the deck plate are not parallel.
 12. The dockleveler of claim 8, wherein the lip includes an upper lip surface, alower lip surface, and a back edge, and the deck-hinge member includesan upper hinge surface such that when the lip is in the extendedposition, the upper lip surface and deck plate create an apex when theback edge of the lip engages the front edge of the deck and the lowerlip surface engages the upper hinge surface.
 13. A dock leveler,comprising: a deck that is movable between a raised position and across-traffic position; a lip pivotally connected to the deck such thatthe lip is pivotal between an extended position and a pendant positionrelative to the deck; a lip-hinge member extending from the lip; a hingepin engaging the lip-hinge member; a deck-hinge member extending fromthe deck such that the deck-hinge member is fixed relative thereto anddefining an aperture through which the lip-hinge member extends; and acurved pin-engaging surface on the deck-hinge member, wherein the curvedpin-engaging surface extends less than 360-degrees around the hinge pinsuch that the hinge pin pivotally couples the lip to the deck.
 14. Thedock leveler of claim 13, wherein the deck-hinge member extends alongmost of the width of the deck.
 15. The dock leveler of claim 13, furthercomprising a plurality of lip-hinge members, wherein the deck-hingemember defines a plurality of apertures through which the plurality oflip-hinge members extend.
 16. The dock leveler of claim 13, wherein thedeck comprises a deck plate supported by a plurality of beams, and thedeck-hinge member defines a plurality of slits into which the pluralityof beams extend.
 17. The dock leveler of claim 13, wherein thedeck-hinge member includes an upper surface that is substantially flatand lies at a non-zero angle to a driveway surface of the deck, so thatthe upper surface of the deck-hinge member and the driveway surface ofthe deck are not parallel.
 18. The dock leveler of claim 13, wherein thedeck includes a driveway surface and a front edge, the lip includes anupper lip surface, a lower lip surface, and a back edge, and thedeck-hinge member includes an upper hinge surface such that when the lipis in the extended position, the upper lip surface and driveway surfacecreate an apex when the back edge of the lip engages the front edge ofthe deck, and the lower lip surface engages the upper hinge surface. 19.The dock leveler of claim 13, wherein the deck includes a deck platesupported by a plurality of beams, the deck plate has a deck width, afront edge, and a plate material thickness, the lip has a lip materialthickness that is greater than the plate material thickness, and furthercomprising a flange lying adjacent to the front edge, running along mostof the deck width, and extending downward from the deck plate to a loweredge of the flange, wherein the lower edge of the flange is higher thana lower extremity of the hinge pin when the deck is at the cross-trafficposition.